1. Field of the Invention
The modification of plants by genetic engineering has lagged behind the understanding and utilization of the molecular biology of unicellular organisims and mammalian cells. Techniques that have proven effective for stable transformation of unicellular microorganisms or mammalian cells with foreign DNA have not found useful analogy with plant cells. Therefore, despite the many achievements involved with unicellular microorganisms and mammalian cells, the number of achievements with plant cells has been substantially fewer and the experience with the other types of organisms has not been readily translatable into successful practices with plant cells.
In many situations it will be desirable to modify an existing trait of a plant cell, rather than introduce a new trait. Thus, one may wish to modify the activity of a particular enzyme, provide for the preferential expression of one allele as compared to another, one isozyme as compared to another, or the like. In many instances one may only wish to reduce the amount of expression of a structural gene, rather than inhibit expression entirely. It is therefore of interest to develop techniques which will allow for directed modification of the phenotype of particular plant cells, plant tissues or plants.
2. Description of the Relevant Literature
Crowley et al. Cell (1985) 43:633-641, describe the use of an anti-sense construct of the discoidin gene transfected into Dictyostelium to repress expression of endogenous discoidin genes. See also references cited therein. Anti-sense regulation has also been described by Rosenberg et al. Nature (1985) 313:703-706; Preiss et al. Nature (1985) 313:27-32; Melton, Proc. Natl. Acad. Sci. U.S.A. (1985) 82:144-148; Izant and Weintraub, Science (1985) 229:345-352; and Kim and Wold, Cell (1985) 42:129-138. See also, Izant and Weintraub Cell (1984) 36:1007-1015; Pestka et al. Proc. Natl. Acad. Sci. U.S.A. (1984) 81:7525-7528; Mizuno et al. ibid (1984) 81:1966-1970; Coleman et al. Cell (1984) 37:683-691; Travers, Nature (1984) 311:410 and Weintraub et al. Trends in Genetics (1985) 1:22-25. McGarry and Lindquist, Proc. Natl. Acad. Sci. U.S.A. (1986) 83:399-403, report the inhibition of heat shock protein synthesis by heat inducible anti-sense RNA.